RC Aerobatics
Eric Henderson, 303 Shady Ln., Marlton NJ 08053; E-mail: [email protected]
A BIG "Thank you" to all who have written in with support, questions, and ideas. It is very gratifying to get such a warm response.
Please keep the ideas and questions coming. I can reply to E-mail very quickly. US mail takes a bit longer, but I will do my best to give a reply whenever a letter needs one.
For many modelers, just getting an airplane built and ready to fly is a major challenge and achievement. Small things, such as getting the engine to run, taking off, then guiding the aircraft down safely, begin as challenges.
However, as a species, we continue to look for new tasks. Aerobatics maneuvers are the challenge many of you have been waiting for.
For me, the challenge is to take you from "boring holes in the sky like a wayward woodpecker" to "carving corners and lines like a Corinthian craftsman."
Types of RC Aerobatics Competition
In Radio Control (RC) Aerobatics, there are three types of competition that employ aerobatic maneuvers: Vintage, Scale, and Precision. (By the end of this column, I will have a fourth type of contest—Fun-Fly Aerobatics [FFA]—as a way to increase interest in all three!)
- Vintage, or Old-Time Pattern, is for pilots who like to fly airplanes from a bygone era—pre-1984, when Precision Aerobatics was much more reachable and much more fun.
Even allowing for "The older I get, the better I was" syndrome, there is much to be learned from the past. Vintage Aerobatics is not flown only by older pilots, as my naming convention might infer. It has a great deal of support among all age groups.
There are two mainstream RC Aerobatics categories today.
- RC Scale Aerobatics, as it is called in the AMA Competition Regulations, is more commonly referred to by its Special Interest Group (SIG) name: IMAC — the International Miniature Aerobatic Club.
This is principally a Scale rendition of what the models' full-scale counterparts do in competition. The airplanes must look like full-scale aircraft. They can be quite large, approximately scale, and are required to have a pilot and an instrument panel.
The aerobatics flown in IMAC are just as difficult as those flown by the full-scale airplanes. The models often replicate the quirks and challenges of the full-scale aircraft.
I'm not an expert on IMAC. Read the "RC Scale Aerobatics" column in Model Aviation and/or visit the magazine's Web site.
I do fly some IMAC, so I have an idea of the degree of difficulty in their schedules, and what it takes to perform them with Scale airplanes. I find them harder to fly than Pattern airplanes.
- RC Pattern, as it is called in the 2000 Competition Regulations. (Call AMA to have a copy of Competition Regulations sent to you.)
Most RC Pattern fliers refer to what they do as "Precision Aerobatics," because the challenge of making an airplane draw precise lines in the sky, roll at exact moments, and execute exact degrees of rotation.
The RC Pattern SIG is the National Society of Radio Controlled Aerobatics (NSRCA).
Pattern airplanes are designed to achieve aerobatic excellence, as opposed to being a Scale model of an existing airplane. There is a never-ending search for the "perfect airplane," which will fly perfectly at all attitudes and in all wind conditions.
AMA regulations require the Pattern airplane to weigh no more than 11 pounds, and to have a size no greater than two meters (approximately 78½ inches) in any direction. With those requirements, an airplane will look approximately the right size when flown at the desired 150 meters away from the judges. The smaller the model, the closer you fly it.
These specifications encourage creative and exotic building techniques and materials.
The above types of Aerobatics have schedules that increase in difficulty as you progress in achievement/results and skill.
What IMAC and RC Pattern have in common is that the maneuvers are flown consecutively; there is no break between each one, other than a straight line. This is referred to as "Turnaround" aerobatics.
The older style was designed to have one maneuver performed at a time. The pilot flew the airplane in front of the judges, did the required maneuver, then exited stage right or left, as the case may be.
This gave the judges think-time and gave the pilot breathing room, sometimes literally, to set up for the next maneuver.
Turnaround and the older style of aerobatics have a common problem: the higher you go in contest classes, the bigger or more expensive both types of airplanes become. A cost of $3,000 or more for a top-of-the-line Pattern or Scale Aerobatics airplane is common.
We need much more fun for much less money. Maneuvers we can fly with our first low-winger would be nice. We need people to try the challenge of Aerobatics competition. I have been calling this the "Pre-Pattern" class, because Pattern is the main theme of this column.
However, RC Aerobatics is a much broader category, and it would be wonderful if the following proposed activities produced pilots that flew all types of AMA Aerobatics.
Fun-Fly Aerobatics (FFA) Concept
The concept of "Fun-Fly Aerobatics" is based on a return to the simpler design of pre-Turnaround aerobatics.
It is possible, and easy, to design a contest that can be run by any club, with or without Precision Aerobatics competition experience. It would be similar to the old-time Pattern formula of performing one centered maneuver at a time. There are several primary operational differences.
This would be a club fun-fly, so it would not need an AMA sanction. The schedule(s) would be designed by the club, which would run as many different classes as it wants to run.
A suggestion is to employ the Loop, Stall Turn, and Roll maneuvers described so far, as a basis for the fun-fly maneuvers. Score each maneuver out of 10, and deduct for primary errors such as centering, roundness, and level flight during the roll. The stall would have five points deducted if it was flopped.
The more-advanced rounds could have consecutive Rolls, Loops, or Stalls. You could even score landings and takeoffs:
- 10 points for no bounce
- 5 points for one bounce
- 0 points for more than two bounces
I will provide more details next month, and I'll put a starter pack online for those who are interested. (Input is/will be most welcome.)
The Horizontal Roll
One key maneuver you will need for the preceding is the Roll. The Horizontal Roll is a "pre-Pattern challenge" that will do wonders for your flying—even if you never compete.
The Horizontal Roll puts fear in the hearts of "wannabe" Aerobatics pilots. In addition to rolling the airplane through 360° with aileron input, you are expected not to lose or gain height. You are required to roll at a constant rate, and stop the rolling action with the model dead level.
(There are also Vertical Rolls, but I will not address them here; they are very different, because gravity has little or no effect on their heading.)
If there was no wind or gravity, there would be no problems with the Horizontal Roll; you would just move the aileron stick over, hold it in position, and move it back just before the roll is completed.
The first thing to do when learning a full roll is to see what the model does when you give it full aileron.
Gain some height, and fly level at roughly 3/4 throttle. Apply aileron to effect a 360° roll. You should see the airplane drop its nose throughout the roll, and finish by diving toward the ground at approximately 15° to 45°.
Throttle back to slow the dive, and proceed to regain height. If the model does not dive, you're probably flying a very tail-heavy airplane. If the aircraft dives a lot, your model is most likely nose-heavy. (All of this assumes a semisymmetrical or symmetrical wing.)
Now you know how much antigravity-corrective input the airplane needs to perform a flat, horizontal roll.
Do a slow roll to the left. Make sure the airplane is flying level, because any diving action will speed things up too much, and will require excessive correction.
As the model rolls left, apply right rudder. When the model is inverted, center the rudder and add a touch of down-elevator. As the airplane continues to roll, add left rudder. When the model is level, remove the rudder.
Find a friend, and ask him/her to read "Left aileron, right rudder, down, left rudder," as you are doing the roll. (Reverse the rudders for a right roll.)
The actual roll will be a bit curvy at first, primarily because you will apply too much rudder input. The main idea is to use the rudder as an elevator when the model is going through the knife-edge attitude of the roll. Keeping the airplane's nose on a horizontal trajectory is the goal.
I still say the short version, "left, right, left, right, left, left," as a support to my memory when I do positive rolls.
Drill: Half-Rolls
For many of us—if not most of us—the preceding instructions can be too much to perform in one go, so there is a useful exercise that has helped many pilots on their way to the perfect Roll. I did this with some friends in England a few weeks ago.
Break the Roll into half-rolls, with a pause in the middle. Do not complete the roll if you fail to keep the nose level in the first half.
Roll the model left, and apply right rudder. Stop the roll when the airplane is inverted, and examine the model's attitude. If it is longitudinally level, roll left again and add left rudder. Stop when level, and examine the airplane's attitude. If it's level and straight, you did it!
Practice 1/2 rolls until you can lock the airplane level inverted, and from inverted to upright again. You soon learn how much rudder deflection to apply, to get the result you need.
The rudder goes in and out, according to where the airplane is in the roll. The maximum amount of rudder is applied in the knife-edge position, and is decreased as the airplane returns to the level position.
As you get better at the 1/2 rolls, the time you pause your model in the inverted position will decrease, until the hesitation is gone completely. Then you will be able to roll an airplane at any height, without the fear of dropping it into the grass.
This exercise is also particularly useful when you're learning to do Four Point Rolls. If you trained yourself to do a Slow Roll this way, a Four Point Roll will be easy to develop.
Using rudder in isolation is not totally correct, but it is a major step toward doing a professional-looking roll.
As you become more sophisticated with the Roll, you will notice that the rudder-only application causes a slight weaving from left to right. You can smooth this out by using a combination of elevator and rudder input, to create an even straighter line.
However, you need to master the two very important half-roll actions before you get there.
Where you do the Roll is as important as how well you do it. To be centered, a roll has to be flown so that the inverted moment is on the centerline. I strongly advise that you practice doing the first half-roll so it stops right on center.
And please practice rolling in both directions; it will be your salvation one day.
I will not address wind correction in a Roll until much later. (It can be done, but I have only seen a few who can or will do it.)
Most Rolls are performed downwind, so practice that way. Airspeed is more important than ground speed, so keep some power on when you go downwind.
All of these maneuvers are on the NSRCA.org Web site, in the "NSRCA Judging Information" section developed by Lamar Blair, or in the 2000 AMA Competition Regulations.
Now you have the practice drills for the Loop, the Stall Turn, and the Horizontal Roll. Combine them into the pre-Pattern schedule concept, and you could have an Aerobatics fun-fly at your club next Sunday.
You could also enter a Pattern contest, if you weren't so shy. Gear up!
MA
Transcribed from original scans by AI. Minor OCR errors may remain.
